Design and development of motorized multileaf collimator for telecobalt unit

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Traditional radiation therapy often relies on customized blocks for beam shaping, which are time-consuming and costly to fabricate.
• Telecobalt units offer a radiation source, but their application in advanced treatment techniques like Intensity-Modulated Radiation Therapy (IMRT) can be limited by collimation methods.

Purpose of the Study:

• To investigate the feasibility and performance of a motorized multileaf collimator (MLC) for a telecobalt unit.
• To compare the efficacy of MLC-based field shaping with conventional customized blocks.
• To evaluate the potential of using the motorized MLC for 3D Conformal Radiation Therapy (3DCRT) and IMRT with Cobalt-60 beams.

Main Methods:

• Motorization of a manual multileaf collimator for a telecobalt unit.
• Characterization of beam properties and measurement of interleaf leakage and transmission.
• Verification of field shaping accuracy using film dosimetry.
• Comparative treatment planning study of 3DCRT and IMRT using Cobalt-60 and 6 MV beams.

Main Results:

• The motorized MLC achieved effective field shaping, with maximum interleaf leakage of 2.7% and transmission of 2.4% at 0.5 cm depth.
• Film dosimetry confirmed the accuracy of MLC-based field shaping.
• Comparative treatment planning indicated that MLC can substitute for customized blocks in static fields, reducing fabrication effort and cost.
• IMRT delivery with Cobalt-60 and MLC was shown to be a cost-effective alternative to IMRT with 6 MV beams.

Conclusions:

• A motorized MLC for telecobalt units is a viable and practical substitute for conventional customized blocks in static fields.
• This system offers significant advantages in terms of cost, effort, and storage space compared to block fabrication.
• Implementing IMRT with Cobalt-60 and MLC presents a cost-effective radiation therapy option.